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Articles indexed in April 2010

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• Searches (and general querying) with HBase and/or Cassandra (best practices?)

  - by alexeypro

  I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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• How to dynamically choose two fields from a Linq query as a result

  - by Dr. Zim

  If you have a simple Linq query like: var result = from record in db.Customer select new { Text = record.Name, Value = record.ID.ToString() }; which is returning an object that can be mapped to a Drop Down List, is it possible to dynamically specify which fields map to Text and Value? Of course, you could do a big case (switch) statement, then code each Linq query separately but this isn't very elegant. What would be nice would be something like: (pseudo code) var myTextField = db.Customer["Name"]; // Could be an enumeration?? var myValueField = db.Customer["ID"]; // Idea: choose the field outside the query var result = from record in db.Customer select new { Text = myTextField, Value = myValueField };

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• How to design Models the correct way: Object-oriented or "Package"-oriented?

  - by ajsie

  I know that in OOP you want every object (from a class) to be a "thing", eg. user, validator etc. I know the basics about MVC, how they different parts interact with each other. However, i wonder if the models in MVC should be designed according to the traditional OOP design, that is to say, should every model be a database/table/row (solution 2)? Or is the intention more like to collect methods that are affecting the same table or a bunch of related tables (solution 1). example for an Address book module in CodeIgniter, where i want be able to "CRUD" a Contact and add/remove it to/from a CRUD-able Contact Group. Models solution 1: bunching all related methods together (not real object, rather a "package") class Contacts extends Model { function create_contact() {) function read_contact() {} function update_contact() {} function delete_contact() {} function add_contact_to_group() {} function delete_contact_from_group() {} function create_group() {} function read_group() {} function update_group() {} function delete_group() {} } Models solution 2: the OOP way (one class per file) class Contact extends Model { private $name = ''; private $id = ''; function create_contact() {) function read_contact() {} function update_contact() {} function delete_contact() {} } class ContactGroup extends Model { private $name = ''; private $id = ''; function add_contact_to_group() {} function delete_contact_from_group() {} function create_group() {} function read_group() {} function update_group() {} function delete_group() {} } i dont know how to think when i want to create the models. and the above examples are my real tasks for creating an Address book. Should i just bunch all functions together in one class. then the class contains different logic (contact and group), so it can not hold properties that are specific for either one of them. the solution 2 works according to the OOP. but i dont know why i should make such a dividing. what would the benefits be to have a Contact object for example. Its surely not a User object, so why should a Contact "live" with its own state (properties and methods). you experienced guys with OOP/MVC, please shed a light on how one should think here in this very concrete task.

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• wordpress post by email and also cats and tags

  - by lil will

  hi, i'm trying to add categories and tags to my posts. how can i achive that if i am posting by email? thanks guys.

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• E-Commerce website using blogging service

  - by Rohit

  I have been selling software products since last few years. I now want to sell them online. I have three ways in my mind: Using TypePad and integrating PayPal code in it. Get designed my own website. Buy a shopping cart online app. like Volusion etc. I am not selling all the products but only selected software products. I want to know which is the best solution in terms on cost, manageability and getting online response.

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• Minimal rsync installation without need for cygwin

  - by Aman Jain

  Is there a way to install rsync on Windows XP without having to use cygwin? I don't want to install cygwin because it takes lot of space. Moreover, I need to make it communicate with a rsync daemon on Linux, therefore alternatives to rsync on Windows won't help.

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• Can one use VMWare vCloud API in its own datacenter

  - by Sergejus

  Currently we're building a small datacenter. For the Infrastructure-as-a-Service part I'm planning to use VMWare vSphere. I know VMWare is pushing its vCloud API so my question is: how can I install and use this API within my own datacenter?

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• disable log4j if log4j.properties file is not found.

  - by zeroin23

  log4j:WARN No appenders could be found for logger ().<br/> log4j:WARN Please initialize the log4j system properly. The above message is shown and i would like to disable the logger if the log4j.properties cannot be found. How do i go about it? BasicConfigurator.configure(); will output to console which is not what i want.

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• .NET application for blackberry?

  - by every_answer_gets_a_point

  i have a very simple winform application in vb.net and i was wondering how do i make it work on blackberry and other PDAs?

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• Move a sequential set of commits from one (local) branch to another

  - by jpswain09

  Is there a way to move a sequential set of commits from one (local) branch to another? I have searched quite a bit and still haven't found a clear answer for what I want to do. For example, say I have this: master A---B---C \ feature-1 M---N---O---P---R---Q And I have decided that the last 3 commits would be better off like this: master A---B---C \ feature-1 M---N---O \ f1-crazy-idea P---R---Q I know I can do this, and it does work: $ git log --graph --pretty=oneline (copying down sha-1 ID's of P, R, Q) $ git checkout feature-1 $ git reset --hard HEAD^^^ $ git checkout -b f1-crazy-idea $ git cherry-pick <P sha1> $ git cherry-pick <R sha1> $ git cherry-pick <Q sha1> I was hoping that instead there would be a more concise way to do this, possibly with git rebase, although I haven't had much luck. Any insight would be greatly appreciated. Thanks, Jamie

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• gdb - thread log

  - by sthustfo

  Hi all, While I trying to debug a 'C' program with gdb, I always get the following continuously on the gdb console. [Thread 0xb7fe4b70 (LWP 30576) exited] [New Thread 0xb7fe4b70 (LWP 30577)] [Thread 0xb7fe4b70 (LWP 30577) exited] [New Thread 0xb7fe4b70 (LWP 30578)] [Thread 0xb7fe4b70 (LWP 30578) exited] Is there any reason why this is printed? And anyway to block this? note: the program makes use of timers. Is that a possible cause?

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• Need Help with Consolidating RoR Google Map Results

  - by Kevin

  I have a project that returns geocoded results within 20 miles of the user. I want these results grouped on the map by zip code, then within the info window show the individual results. The code posted below works, but for some reason it only displays the 1.png rather than looking at the results and using the correct .png icon associated with the number. When I look at the infowindows, it displays the correct png like "/images/2.png" or "/images/5.png" but the actual image is always 1. @ziptickets = Ticket.find(:all, :origin => coords, :select => 'DISTINCT zip, lat, lng', :within => @user.distance_to_travel, :conditions => "status_id = 1") for t in @ziptickets zips = Ticket.find(:all, :conditions => ["zip = ?", t.zip]) currentzip = t.zip.to_s tixinzip = zips.size.to_s imagelocation = "/images/" + tixinzip + ".png" shadowlocation = "/images/" + tixinzip + "s.png" @map.icon_global_init(GIcon.new(:image => imagelocation, :shadow => shadowlocation, :shadow_size => GSize.new(60,40), :icon_anchor => GPoint.new(20,20), :info_window_anchor => GPoint.new(9,2)), "test") newicon = Variable.new("test") new_marker = GMarker.new([t.lat, t.lng], :icon => newicon, :title => imagelocation, :info_window => currentzip) @map.overlay_init(new_marker) end I tried changing the last part of the mapicon from: :info_window_anchor => GPoint.new(9,2)), "test") newicon = Variable.new("test") to: :info_window_anchor => GPoint.new(9,2)), currentzip) newicon = Variable.new(currentzip) but the strangest thing is that any string that has numbers in it causes the map to fail to render in the view and just show a blank screen... same if I replace it with :info_window_anchor => GPoint.new(9,2)), "123") newicon = Variable.new("123") Any advice would be helpful... also it runs a bit slower than my previous code which just set up 4 standard icons and used them outside of the loop so any hints as to speed up execution would be appreciated greatly. Thanks!

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• Customize ToolStripMenuItem

  - by Lu Lu

  Hello everyone, I want to customize ToolStripMenuItem by overriding OnPaint function. This is a MyToolStripMenuItem: public class MyToolStripMenuItem : ToolStripMenuItem { public MyToolStripMenuItem() :base() { } public MyToolStripMenuItem(string t) :base(t) { } protected override void OnPaint(PaintEventArgs e) { Graphics g = e.Graphics; Rectangle r = this.Bounds; g.FillRectangle(Brushes.Blue, r); g.DrawString(this.Text, this.Font, Brushes.Red, r); } } In my code, I will fill a blue color in item's bound. Now, I will create a list of items on menustrip: MyToolStripMenuItem1 |___MyToolStripMenuItem2 |___MyToolStripMenuItem3 I don't know why MyToolStripMenuItem3 don't have a blue background. This is my source code: http://www.mediafire.com/?2qhmjzzfzzn Please help me. Thanks.

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• which one run faster in mysql

  - by hd

  which one run faster in mysql: a query with multiple joins or that query with using nested select?

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• how to access vista system remotely using vb.net ?

  - by meenakshi

  I tried to access xp to vista system manually, its working,but programatically how to do it ? like,by selecting view workgroup computers in network tasks and click one computer in workgroup computers.it shows connect to "system name" window, contains username and password if i enter username and password.the seleted computer will able to access in registry otherwise i can't able to access that selected system. how to do this manual process in vb.net coding? is it possible or not? please help me

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• Constant NSDictionary/NSArray for class methods.

  - by Jeff B

  I am trying to code a global lookup table of sorts. I have game data that is stored in character/string format in a plist, but which needs to be in integer/id format when it is loaded. For instance, in the level data file, a "p" means player. In the game code a player is represented as the integer 1. This let's me do some bitwise operations, etc. I am simplifying greatly here, but trying to get the point across. Also, there is a conversion to coordinates for the sprite on a sprite sheet. Right now this string-integer, integer-string, integer-coordinate, etc. conversion is taking place in several places in code using a case statement. This stinks, of course, and I would rather do it with a dictionary lookup. I created a class called levelInfo, and want to define the dictionary for this conversion, and then class methods to call when I need to do a conversion, or otherwise deal with level data. NSString *levelObjects = @"empty,player,object,thing,doohickey"; int levelIDs[] = [0,1,2,4,8]; // etc etc @implementation LevelInfo +(int) crateIDfromChar: (char) crateChar { int idx = [[crateTypes componentsSeparatedByString:@","] indexOfObject: crateChar]; return levelIDs[idx]; } +(NSString *) crateStringFromID: (int) crateID { return [[crateTypes componentsSeparatedByString:@","] objectAtIndex: crateID]; } @end Is there a better way to do this? It feels wrong to basically build these temporary arrays, or dictionaries, or whatever for each call to do this translation. And I don't know of a way to declare a constant NSArray or NSDictionary. Please, tell me a better way....

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• Why does ANT tell me that JAVA_HOME is wrong when it is not?

  - by Ankur

  I get the error: C:\dev\ws\springapp\build.xml:81: Unable to find a javac compiler; com.sun.tools.javac.Main is not on the classpath. Perhaps JAVA_HOME does not point to the JDK. It is currently set to "C:\Program Files\Java\jre6" But I have clearly set my JAVA_HOME to be C:\Program Files\Java\jdk1.6.0_14 Where is ANT getting this value?

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• Java IO (javase 6)- Help me understand the effects of my sample use of Streams and Writers...

  - by Daddy Warbox

  BufferedWriter out = new BufferedWriter( new OutputStreamWriter( new BufferedOutputStream( new FileOutputStream("out.txt") ) ) ); So let me see if I understand this: A byte output stream is opened for file "out.txt". It is then fed to a buffered output stream to make file operations faster. The buffered stream is fed to an output stream writer to bridge from bytes to characters. Finally, this writer is fed to a buffered writer... which adds another layer of buffering? Hmm...

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• What does the -P option do to mount?

  - by Simon

  I'm migrating from an archaic version of Red Hat to Ubuntu 9. When going through my old nfs mount script, I found that it contained the -P option. So my script looks like: sudo mount -t nfs -o -P ... It looks like the -P is one of the -o options. My question is: what does the -P option do? I've searched every man page I can find, with no luck. Could it have to do with privileged ports?

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• Looking for .NET library to create PDF

  - by aximili

  We are looking for a .NET PDF creator. It needs to be .NET, so we can just copy the file(s) onto the server, not having to install anything. We only need to create a PDF with some text and images and a heading, that's all. Anyone know a good one? We are happy to buy if there is a good one that is easy to use. Thanks in advance.

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• sqrt(int_value + 0.0) ? The point?

  - by Earlz

  Hello, while doing some homework in my very strange C++ book, which I've been told before to throw away, had a very peculiar code segment. I know homework stuff always throws in extra "mystery" to try to confuse you like indenting 2 lines after a single-statement for-loop. But this one I'm confused on because it seems to serve some real-purpose. basically it is like this: int counter=10; ... if(pow(floor(sqrt(counter+0.0)),2) == counter) ... I'm interested in this part especially: sqrt(counter+0.0) Is there some purpose to the +0.0? Is this the poormans way of doing a static cast to a double? Does this avoid some compiler warning on some compiler I do not use? The entire program printed the exact same thing and compiled without warnings on g++ whenever I left out the +0.0 part. Maybe I'm not using a weird enough compiler?

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• Deleting a non-owned dynamic array through a pointer

  - by ayanzo

  Hello all, I'm relatively novice when it comes to C++ as I was weened on Java for much of my undergraduate curriculum (tis a shame). Memory management has been a hassle, but I've purchased a number books on ansi C and C++. I've poked around the related questions, but couldn't find one that matched this particular criteria. Maybe it's so obvious nobody mentions it? This question has been bugging me, but I feel as if there's a conceptual point i'm not utilizing. Suppose: char original[56]; cstr[0] = 'a'; cstr[1] = 'b'; cstr[2] = 'c'; cstr[3] = 'd'; cstr[4] = 'e'; cstr[5] = '\0'; char *shaved = shavecstr(cstr); delete[] cstrn; where char* shavecstr(char* cstr) { size_t len = strlen(cstr); char* ncstr = new char[len]; strcpy(ncstr,cstr); return ncstr; } In that the whole point is to have 'original' be a buffer that fills with characters and routinely has its copy shaved and used elsewhere. To prevent leaks, I want to free up the memory held by 'shaved' to be used again after it passes through some arguments. There is probably a good reason for why this is restricted, but there should be some way to free the memory as by this configuration, there is no way to access the original owner (pointer) of the data.

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• jQuery Equal Height Divs

  - by griegs

  If i have the following harkup; <div> <div> <div id='sameHeight'>One<br>two<br>three</div> <div id='sameHeight'>four</div> <div id='sameHeight'>five</div> <div> <div> <div id='sameHeight'>four</div> <div id='sameHeight'>six</div> <div id='sameHeight'>seven<br>eight</div> <div> </div> How can I ensure that all divs marked as "sameHeight" are the same height as their counterparts in the other div? I had a look at equalHeights plugin but that assumes all divs side by side are in the same parent. I need one that can either traverse parents or allow me to specify parents. Is there such a thing or do I need to write it?

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• SharePoint Custom Web Service not working for SSL configuration

  - by Carol

  Hi all, I did developed a custom SharePoint Web Service . It is working fine when using http. But when we configure SSL(https) , it is not working and throwing the below error. Request for the permission of type 'Microsoft.SharePoint.Security.SharePointPermission, Microsoft.SharePoint.Security, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bcee11233hj' failed. Does anyone came accross a similar situation or any ideas on why this is happening? Thanks Carol

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• visual studio 2008 linker error

  - by ravi

  In visual studio 2008, I have created a static dll called test_static.dll. I am trying to call this from one application. I have included this dll in source files folder and the header file related to it in headers folder. When i am running the application I am getting following liking error. Please give me a solution. error LNK2019: unresolved external symbol "struct morph_output * __cdecl morpho_data(struct morph_input *)" (?morpho_data@@YAPAUmorph_output@@PAUmorph_input@@@Z) referenced in function _wmain 1D:\test_app\Debug\test_app.exe : fatal error LNK1120: 1 unresolved externals 1Build log was saved at "file://d:\test_app\test_app\Debug\BuildLog.htm" Here test_app is application that is using static dll. and morpho_data is the dll function which is taking input as structure and returning another structure.

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